Google uses the titles to track things. So yes, you can toss it once in a header.php file for a e-commerce store or a blog, and it will count as separate pages as long as the titles are different.
That is, if you have it set up with every item having it`s own unique title ... which it should.
ZenCart is not "osCommerce lite" or however it was phrased. It`s a very good piece of software, high customizable and designer-friendly with the stylesheets. They both have their pros and cons, but IMO ZenCart looks a little better out of the box.